Torque transmitting systems of the epicyclic type are quite well known for their utility as speed reduction mechanisms. Typically, an orbiting internal pinion gear will be provided with one or a few less teeth than an outer ring gear, such that a quite large speed reduction can be obtained between the input and an output appropriately coupled to the pinion gear.
Gear systems of this type, however, suffer from a number of disabilities. In particular, they are expensive to produce, inasmuch as the gears must be precisely cut. Moreover, such devices can transmit only a limited amount of torque due to the fact that only some fraction of the gear teeth are in contact at any given instant. Additionally, input, output and intermediate bearing sets have always been necessary in such systems, often in double sets, in order to accommodate large loads on the gearing elements, and adding to the cost of such gearing systems.
The only known example of a prior art system operating somewhat similarly to the present construction is disclosed in U.S. Pat. No. 1,738,662 to Morison. This patent relates to a ball drive transmission wherein an input shaft 11 bears upon and rotatably drives a set of three balls 21-23 where one ball has a smaller diameter than the other two. This diameter difference causes a ring 32 disposed surrounding the balls to orbit about the axis of the input shaft as the balls rotate. The orbiting ring 32 serves as an input to the epicyclic gearing mechanism which comprises a plurality of balls held by means of a cage 6.
An outer stationary ring is formed with a plurality of indentations equal to the number of balls +1. In operation, the orbiting ring 32 successively forces the balls into the indentations such that the balls roll from one indentation to another. As they do so, the cage 6 is made to rotate, and the output is taken off from this element.
Although quite different in structure and operation, the Morison patent is seen to generally teach the idea of torque transmitting elements which roll or circulate during operation.